<?php
/**

*+----------------------------------------------------------

* 字符串截取，支持中文和其他编码

*+----------------------------------------------------------

* @static

* @access public

*+----------------------------------------------------------

* @param string $str 需要转换的字符串

* @param string $start 开始位置

* @param string $length 截取长度

* @param string $charset 编码格式

* @param string $suffix 截断显示字符

*+----------------------------------------------------------

* @return string

*+----------------------------------------------------------

*/

function msubstr($str, $start=0, $length, $charset="utf-8", $suffix=true){

  if(function_exists("mb_substr")){

     if($suffix){

      return mb_substr($str, $start, $length, $charset)."...";

     }else{

      return mb_substr($str, $start, $length, $charset);

     }

  }elseif(function_exists('iconv_substr')) {

       if($suffix){

            return iconv_substr($str,$start,$length,$charset)."...";

       }else{

        return iconv_substr($str,$start,$length,$charset);

       }

  }

    $re['utf-8']   = "/[\x01-\x7f]|[\xc2-\xdf][\x80-\xbf]|[\xe0-\xef][\x80-\xbf]{2}|[\xf0-\xff][\x80-\xbf]{3}/";

    $re['gb2312'] = "/[\x01-\x7f]|[\xb0-\xf7][\xa0-\xfe]/";

    $re['gbk']    = "/[\x01-\x7f]|[\x81-\xfe][\x40-\xfe]/";

    $re['big5']   = "/[\x01-\x7f]|[\x81-\xfe]([\x40-\x7e]|\xa1-\xfe])/";

    preg_match_all($re[$charset], $str, $match);

    $slice = join("",array_slice($match[0], $start, $length));

    if($suffix){ 

        return $slice."...";

    }else{

        return $slice;

    }

}